This application is based on Patent Application No. 2000-396148 filed Dec. 26, 2000 in Japan, the content of which is incorporated hereinto by reference.
1. Field of the Invention
The present invention relates to an IC socket with two point-contacts, and more specifically, to an IC socket with two point-contacts which restrict the tracks of contacts that may contact with a lead terminal of an IC package to prevent the lead terminal from being deformed.
2. Description of the Related Art
IC sockets with two point-contacts have been commonly used because of their capability of reliably measuring the characteristics of IC packages at a high speed. An IC socket with two point-contacts and the operation of installing a IC package on an IC socket will be described in brief with reference to FIG. 3.
FIG. 3A shows a socket free state in which no IC package is installed on an IC socket. In this figure, the IC socket 1 is composed of a contact 2, a base 8, a platform 7, and a cover 9. The contact 2 is composed of a pair of contact portions 4 and 5 that sandwich a lead terminal 12 of an IC package 11, a pressure receiving section 3 that engages with a contact opening cam 10 of the cover 9 to move the pair of contact portions 4 and 5, and a terminal portion 6 that projects downward from the base 8. A large number of elastic contacts 2 are arranged on the base 8 in a direction perpendicular to the sheet of the drawing. The IC package 11 is placed on the platform 7. Further, the cover 9 is urged and biased upward by a coil spring (not shown).
To install the package 11 on the IC socket 1 constructed as described above, the cover 9 is first subjected to a pressure corresponding to a full stroke, as shown in FIG. 3B. The pressure receiving section 3 of the contact 2 engages with contact opening cam 10 of the cover 9 and moves along the opening cam 10. Thereby the contact portions 4 and 5 of the contact 2 also move backward (right side contact moves rightward in the drawing).
Then, the IC package 11 is placed on the platform 7, and the cover 9 is subsequently released. Then, the pair of contact portions 4 and 5 of the contact 2 move forward or return to their original portions, while the lead terminal 12 of the IC package 11 placed on the platform 7 is sandwiched between the contact portions 4 and 5 (see FIG. 3C).
After the IC package 11 has been tested, the cover 9 is subjected to a pressure corresponding to a full stroke to move the contact portions 4 and 5 backward, while the lead terminal 12 is released from the contact portions 4 and 5 to allow the IC package 11 to be removed from the IC socket 1.
When the lead terminal 12 of the IC package 11 is sandwiched between the pair of contact portions 4 and 5, the motion of the contact portions 4 and 5 is controlled by the shape of the contact opening cam 10 provided on the cover 9. However, although the above described IC socket with two point-contacts is characterized by allowing the characteristics of the IC package to be reliably measured at a high speed, good electric contact is not always achieved partly owing to the shape of the lead terminal 12 and regardless of the shape of the contact opening cam 10.
This will be described with reference to FIG. 4. In this figure, the pair of contact portions 4 and 5 sandwich the lead terminal 12 therebetween while moving in the direction shown by the arrow in the figure. At this time, depending on the shape of the lead terminal 12, the lower contact portion 5, which comes in contact with the lead terminal 12 from below, abuts against an end of the lead terminal 12 to deform the lead terminal 12 (see the parts of the figure shown by the solid lines). This results in bad contact or in the worst case, hinders the lead terminal 12 from being sandwiched therebetween. Further, even if the lead terminal 12 is successfully sandwiched between the contact portions 4 and 5, it is pressed by the upper contact portion 4, which comes in contact with the lead terminal 12 from above, and is thus deformed downward (see the parts of the figure shown by the dot lines), depending on its shape. In some cases, the lower contact portion 5 cannot come in contact with the lead terminal 12.
It is an object of the present invention to provide an IC socket constituted to restrict the tracks of the pair of contact portions, while allowing the pair of contact portions to contact with the lead terminal under a uniform pressure.
An IC socket with two point-contacts according to the present invention is characterized by comprising contacts each having a pair of contact portions that sandwich a lead terminal of an IC package therebetween and that are urged and biased by elastic force in a direction in which the contact portions sandwich the lead terminal therebetween, and a contact track restricting means arranged between each pair of contact portions to restrict motion thereof.
Further, the IC socket with two point-contacts according to the present invention is characterized in that the contact track restricting means comprise at least a parallel portion, and the pair of contact portions each comprise an inclined surface on an inner side of a neighborhood of a tip thereof.
Furthermore, the IC socket with two point-contacts according to the present invention may further comprise a cover so that in response to vertical movement of the cover, the pair of contact portions of each contact move forward and backward along the contact track restricting means relative to the lead terminal of the IC package.